Previous issues of this newsletter have discussed how an inability to arrive at correct definitions of various health disorders and how to diagnose them accurately will compromise the effectiveness of treatments that are administered. The October 2022 edition indicated that many scholars have noted that the concept of stigma is defined inconsistently throughout the literature, and that it is measured with different instruments. Similarly, the July-August 2022 issue pointed out that effectiveness in academic and clinical communication depends upon agreement on what words and concepts denote and on the consequent ability to argue logically and accurately. In the pain medicine literature, for example, unfortunately there are many examples of imprecision and confusion in this respect, including misnomers and fallacies in reasoning.
It is likely that readers of this newsletter at one time or another have experienced a headache. The entire August 2022 issue of the journal Seminars in Neurology is devoted to a discussion of this disorder. According to that publication, the first coherent headache classification is seen in writings dating back to the 1st century AD. More recently, the first significant modern attempt at classifying headache disorders was done by an ad hoc committee of the NIH in 1962. The system created that year relied on accepted ideas about headache diagnostic classes, including “vascular headaches” and “muscle contraction headaches.” Although there was little evidence for these categories, and the diagnostic definitions were vague, that “ad hoc committee” classification system was used worldwide for many years. Ultimately, its shortcomings were felt to be more of a barrier than an asset in developing a useful tool for both research and clinical needs.
Defining the epidemiology of headache disorders is challenging given the prevalence of stigma and other harmful misconceptions about these diseases. Understanding the widespread impact of such disorders is essential when considering social and policy interventions to mitigate their impact on health status. Tension-type headache still is considered the most common primary headache disorder, but population-based estimates of its prevalence vary widely. Migraine remains the most common headache disorder in patients who receive clinical care. Prevalence estimates have remained fairly stable over the last two decades, with a one-year period prevalence in the U.S. of 18% of women and 6% of men. Studies in the U.S. also show an inverse relationship between income level and migraine incidence and prevalence, particularly for chronic migraine. Factors mediating this relationship are difficult to define.
The burden of migraine is enormous. The Global Burden of Disease study indicates migraine is the number one cause of disability in women younger than 50 years of age and the number two or three cause of disability worldwide. Further study is needed into underdiagnosis, undertreatment, and persistent stigma associated with headache disorders, especially in underserved communities. Headaches constitute just one more health problem where more clarity and less ambiguity are needed.